F- regulate the preparation of polyhedral BiVO4 enclosed by High-Index facet and enhance its photocatalytic activity

The selective exposure of high-index facets at the surface of nanocrystals is an important and challenging research topic. Herein, polyhedral bismuth vanadate (BiVO4) crystals predominantly surrounded by {2 1 3} and {1 2 1} high-index facets were fabricated through the engineering of high-index surfaces by fluorinion (F-) mediated hydrothermal process. The as-prepared BiVO4-0.2F (the feeding amount of NaF was 0.2 g) catalyst exhibited high apparent quantum efficiency of 17.7% under 420 nm light irradiation and 9.3 fold enhancement of O2 evolution relative to its low-index counterparts. Moreover, the growth of high-index facets results in significant enhancement of hydroxyl radical (•OH) production, photocatalytic degradation of Rhodamine B (RhB) and photoelectrochemical (PEC) properties by the BiVO4 polyhedron, relative to its low-index counterparts. The enhanced photoreactivity is the result of the synergistic effect of F- on the surface of the BiVO4 crystals and exposed high-index facets. For one thing, F- on the surface of the BiVO4 facilitate the separation and transport of photo-induced charge carriers. For another, the exposed high-index facets on polyhedral BiVO4 provided much more reactive sites for photocatalytic reactions. Hopefully, this F- mediated method will be a useful guideline for designing and synthesizing novel high-index faceted micro-/nanostructures for overcoming the practical energy and environment problems.